Results for “Space frames” — Page 69

NASA NTRS1987

Pick-up ions at Comet P/Halley's bow shock - Observations with the IIS spectrometer on Giotto

Gaseous material expanding from the nucleus of Comet Halley into space forms the neutral coma around the comet. Ionization in the solar UV radiation removes particles from the coma and injects them into the solar wind plasma. These freshly created ions are accelerated by the interplanetary electric field on cycloidal trajectories with gyrocenters moving with the speed of the magnetic field lines. In the solar wind frame of reference these particles move along the magnetic field lines with a fixed pitch angle. Pitch-angle scattering and energy diffusion reduce quickly the initial energy anisotropy which is associated with the narrow pick-up structures. First observations of heavy cometary pick-up ions (water group ions) at the bow shock are presented. The evolution of the distribution function in the vicinity of the shock and radial density profiles are discussed.

Wilken, B.↗

NASA NTRS1991

Ion distributions at the dayside magnetopause

Ion phase space distribution, from the AMPTE UKS ion instrument, for a crossing of the dayside magnetopause on October 2, 1984, during typical southward IMF conditions are presented. D-shaped field-aligned phase space distributions of magnetosheath plasma earthward of and hot magnetospheric ions sunward of the magnetopause current layer are observed. The existence of such D-shaped magnetosheath plasma distributions has been predicted as a signature of reconnection. In addition, the observed ion distributions are in stress balance across the magnetopause, and the de Hoffman-Teller frame velocity obtained from the stress balance calculation is in agreement with the observed distribution function cutoff speed. These new observations thus provide further evidence that, at least for southward IMF conditions, reconnection is an important mechanism by which solar wind plasma penetrates into the magnetosphere.

Smith, M. F.↗

NASA NTRS1992

Meteoroid, and debris special investigation group preliminary results: Size-frequency distribution and spatial density of large impact features on LDEF

All craters greater than or equal to 500 microns and penetration holes greater than or equal to 300 microns in diameter on the entire Long Duration Exposure Facility (LDEF) were documented. Summarized here are the observations on the LDEF frame, which exposed aluminum 6061-T6 in 26 specific directions relative to LDEF's velocity vector. In addition, the opportunity arose to characterize the penetration holes in the A0178 thermal blankets, which pointed in nine directions. For each of the 26 directions, LDEF provided time-area products that approach those afforded by all previous space-retrieved materials combined. The objective here is to provide a factual database pertaining to the largest collisional events on the entire LDEF spacecraft with a minimum of interpretation. This database may serve to encourage and guide more interpretative efforts and modeling attempts.

See, Thomas H.↗

NASA NTRS2000

International Laser Ranging Service (ILRS): Terms of Reference

The International Laser Ranging Service (ILRS) is an established Service within Section II , Advanced Space Technology, of the International Association of Geodesy (IAG). The primary objective of the ILRS is to provide a service to support, through Satellite and Lunar Laser Ranging data and related products, geodetic and geophysical research activities as well as International Earth Rotation Service (IERS) products important to the maintenance of an accurate International Terrestrial Reference Frame (ITRF). The service also develops the necessary standards/specifications and encourages international adherence to its conventions.

Husson, Van↗

NASA NTRS2006

Reconfigurable Protocol Sensing in an End-to-End Demonstration

In this work, we present sensing performance using an architecture for a reconfigurable protocol chip for spacebased applications. Toward utilizing the IP packet architecture, utilizing data link layer framing structures for multiplexed data on a channel are the targeted application considered for demonstration purposes. Specifically, we examine three common framing standards and present the sensing performance of these standards and their relative de-correlation metrics. Some analysis is performed to investigate the impact of lossy links. Finally, we present results on a demonstration platform that integrated reconfigurable sensing technology into the Ground Station Interface Device (GRID) for End-to-End IP demonstrations in space.

space based applications↗

NASA NTRS2010

Inertia and Double Bending of Light from Equivalence

Careful examination of light paths in an accelerated reference frame, with use of Special Relativity, can account fully for the observed bending of light in a gravitational field, not just half of it as reported in 1911. This analysis also leads to a Machian formulation of inertia similar to the one proposed by Einstein in 1912 and later derived from gravitational field equations in Minkowsky Space by Sciama in 1953. There is a clear inference from equivalence that there is some type of inertial mass increase in a gravitational field. It is the purpose of the current paper to suggest that equivalence provides a more complete picture of gravitational effects than previously thought, correctly predicting full light bending, and that since the theory of inertia is derivable from equivalence, any theory based on equivalence must take account of it. Einstein himself clearly was not satisfied with the status of inertia in GRT, as our quotes have shown. Many have tried to account for inertia and met with less than success, for example Davidson s integration of Sciama s inertia into GRT but only for a steady state cosmology [10], and the Machian gravity theory of Brans and Dicke [11]. Yet Mach s idea hasn t gone away, and now it seems that it cannot go away without also disposing of equivalence.

Shuler, Robert L., Jr.↗

NASA NTRSDate not supplied

Interoperable Services to Mitigate Lunar Position, Navigation, and Timing Challenges

Across the Earth, both civilian and government endeavors enjoy a built-in reliance on a position, navigation, and timing (PNT) infrastructure to which they are largely blind. Whether walking, driving, flying, or orbiting, Earth-centric PNT systems that have evolved over decades provide a core functionality to which we have grown accustomed for these pursuits. As NASA joins with other government space agencies and commercial partners to return humans to the Moon in a sustained manner within the current decade, expectations for PNT knowledge and timeliness at the Moon rival those on Earth. The need exists to develop a viable lunar-centric PNT infrastructure to support the planned human and robotic exploits. Navigating within the influence of the Moon presents its own set of challenges. Identification, understanding, and use of a unified reference frame and time system on which navigation is based becomes a fundamental need at the Moon. In addition to the unified foundational elements, measurement liability, dynamic conditions that require Earth-independent autonomous operations, and standards for PNT signals and message-based data exchange each represent distinct challenges to navigation in a burgeoning operational lunar environment. The PNT services planned as part of the lunar communications and navigation relay architecture known as LunaNet aid in surmounting the challenges. LunaNet interoperability specifications stipulate standards for signal parameters, messages, and lunar reference systems for PNT services. Within LunaNet’s defined interoperability resides the concept of a Reference Signal to provide communication signals specifically structured to enable measurement of pseudorange, Doppler, and time transfer by the recipient. One such signal type, the Augmented Forward Signal (AFS), functions as the mainstay for LunaNet PNT, while also serving the data needs for ubiquitous broadcast of network access and rapid unscheduled dissemination of alerts and messages. The presence of a geometrically distributed network of orbiting nodes transmitting the AFS forms the basis for the Lunar Augmented Navigation System (LANS), that delivers both radio navigation and data to multiple users in the lunar environment simultaneously. After reviewing the challenges associated with lunar navigation, this paper will describe the concepts and rationale behind the LunaNet PNT services. By borrowing techniques from Earth-centric Global Navigation Satellite Services (GNSS), the Tracking and Data Relay Satellite System, and the Consultative Committee for Space Data Standards, PNT from LunaNet aids to overcome challenges faced for accurate lunar navigation.

LunaNet↗

NASA NTRSDate not supplied

Interoperable Services to Mitigate Lunar Position, Navigation, and Timing Challenges

Across the Earth, both civilian and government endeavors enjoy a built-in reliance on a position, navigation, and timing (PNT) infrastructure to which they are largely blind. Whether walking, driving, flying, or orbiting, Earth-centric PNT systems that have evolved over decades provide a core functionality to which we have grown accustomed for these pursuits. As NASA joins with other government space agencies and commercial partners to return humans to the Moon in a sustained manner within the current decade, expectations for PNT knowledge and timeliness at the Moon rival those on Earth. The need exists to develop a viable lunar-centric PNT infrastructure to support the planned human and robotic exploits. Navigating within the influence of the Moon presents its own set of challenges. Identification, understanding, and use of a unified reference frame and time system on which navigation is based becomes a fundamental need at the Moon. In addition to the unified foundational elements, measurement liability, dynamic conditions that require Earth-independent autonomous operations, and standards for PNT signals and message-based data exchange each represent distinct challenges to navigation in a burgeoning operational lunar environment. The PNT services planned as part of the lunar communications and navigation relay architecture known as LunaNet aid in surmounting the challenges. LunaNet interoperability specifications stipulate standards for signal parameters, messages, and lunar reference systems for PNT services. Within LunaNet’s defined interoperability resides the concept of a Reference Signal to provide communication signals specifically structured to enable measurement of pseudorange, Doppler, and time transfer by the recipient. One such signal type, the Augmented Forward Signal (AFS), functions as the mainstay for LunaNet PNT, while also serving the data needs for ubiquitous broadcast of network access and rapid unscheduled dissemination of alerts and messages. The presence of a geometrically distributed network of orbiting nodes transmitting the AFS forms the basis for the Lunar Augmented Navigation System (LANS), that delivers both radio navigation and data to multiple users in the lunar environment simultaneously. After reviewing the challenges associated with lunar navigation, this paper will describe the concepts and rationale behind the LunaNet PNT services. By borrowing techniques from Earth-centric Global Navigation Satellite Services (GNSS), the Tracking and Data Relay Satellite System, and the Consultative Committee for Space Data Standards, PNT from LunaNet aids to overcome challenges faced for accurate lunar navigation.

Navigation↗

NASA NTRS2000

The Space Interferometry Mission

In this paper we outline the design of the SIM Instrument, and how it will be used in the search for extrasolar planets. We also briefly describe some selected topics from the SIM astrometric science program.

interferometry↗

DOE OSTI2016

Azimuthal distributions in radiative decay of a polarized τ lepton

We investigate various distributions over emitted photon angles, especially over the azimuthal angle, in the one-meson radiative decay of the polarized τ lepton, τ{sup –} → π{sup –}γν{sub τ}. In connection with this, the photon phase space is discussed in more detail because it is nontrivial in the case of a polarized τ lepton. The decay matrix element contains both the inner bremsstrahlung and the resonance (structural) contributions. The azimuthal dependence of some observables are calculated. They are the asymmetry of the differential decay width caused by the τ-lepton polarization, the Stokes parameters of the emitted photon itself, and the correlation parameters describing the influence of τ-lepton polarization on the photon Stokes parameters. A numerical estimation is done in the τ-lepton rest frame for an arbitrary direction of the τ-lepton polarization 3-vector. The vector and axial-vector form factors describing the structure-dependent part of the decay amplitude are determined using the chiral effective theory with resonances (RχT). It is found that the features of the azimuthal distributions allows separating various terms in the spin-dependent contribution. The so-called up–down and right–left asymmetries are also calculated.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2018

Comparison of Doubly-Fed Induction Generator Machine Models for Real-Time Simulations

This work presents a detailed comparison among three implementations of the Doubly-Fed Induction Generator (DFIG) machine model. The alpha-beta-gamma, synchronous (dqo), and natural frame dynamic machine models were deployed on a Field-Programmable Gate Array (FPGA) and compared in terms of execution time and resource utilization. These machine models were also validated against a physical DFIG machine during balanced and unbalanced grid conditions. A benchmark is presented with the objective of selecting the machine model, orientation and state-space representation that is best suited for real-time simulations. The selected machine model is used to develop a real-time emulator of a Type-3 wind system. This emulator enables the study of wind turbine system in realtime using a validated platform while allowing controller testing without relying on expensive third-party solutions.

Ferrari Maglia, Max↗

DOE OSTI2016

Evaluation of the U.S. Department of Energy Challenge Home Program Certification of Production Builders - Chicago, IL and Devens, MA

TO4 Task 3.1 - K Hovnanian Chicago, IL DOE Challenge Home Program Certified Home Constructed and Verified Specifications DOE Challenge Home Building envelope Ceiling R-49 blown fiberglass, Grade I Walls 2x4 framing @ 16 o.c. with R-13 fiberglass batts, Grade I and 1"" R-5 extruded polystyrene (XPS) insulating sheathing Frame Floors R-38 blown fiberglass, Grade I Basement Walls R-19 fiberglass batts draped full height, Grade I Basement Slab uninsulated Windows Above Grade: ENERGY STAR certified, U=0.29, SHGC=0.28 Basement: Non ENERGY STAR certified, U=0.29, SHGC=0.24 Infiltration 2 ACH 50 Mechanical systems Heat 95% AFUE sealed combustion natural gas furnace in conditioned space Goodman GMH950703BXAF Cooling 13 SEER split system Goodman GSX130301BC DHW AO Smith Vertex 100 0.96 EF natural gas tank water heater in 2nd floor utility closet Hot Water Distribution Redesigned trunk and branch Compliant with EPA WaterSense Efficient Distribution Requirements Ducts Located 100% in conditioned space via floor joists leak free to outside (5% or less) Ventilation Central Fan Integrated Supply (CFIS) ventilation with 6"" insulated outside air duct Fan Controller: Air Cycler FRV, with 6"" motorized damper 50 CFM outside air flow, 33% duty cycle (10 minutes on, 20 minutes off); ASHRAE 62.2-2010 compliance via an exhaust fan - Panasonic FV-08VQ5 WhisperCeiling Rerturn Pathways Active Return at Master Bedroom Transfer Grilles in Secondary Bedrooms Appliances, Lighting, MELs Lights 80% ENERGY STAR certified CFL Appliances ENERGY STAR certified refrigerator, dishwasher, and clothes washer; Natural gas range/oven and clothes dryer" STRUCTURE - Test House Lot 145 - 2013 DOE Challenge Test House Task 3.1 Bolingbrook, IL 60490 House is constructed and is DOE Challenge Verified by Don Nelson, a local rater. The purpose of this project was to evaluate integrated packages of advanced measures in individual test homes to assess their performance with respect to Building America Program goals, specifically compliance with the DOE Challenge Home Program. To that end, Building Science Corporation (BSC) consulted on the construction of five test houses by three cold climate production builders in three separate U.S. cities. (1) K. Hovnanian Homes, Chicago, Illinois (2) David Weekley Homes, Denver, Colorado (3) Transformations, Inc., Devens, Massachusetts. Overall, the builders have concluded that the energy related upgrades (either through the prescriptive or performance path) represent reasonable upgrades. The builders commented that while not every improvement in specification was cost effective (as in a reasonable payback period), many were improvements that could improve the marketability of the homes and serve to attract more energy efficiency discerning prospective homeowners. However, the builders did express reservations about the associated checklists and added certifications. An increase in administrative time was observed with all builders. The checklists and certifications also inherently increase cost due to: (1) Adding services to the scope of work for various trades, such as HERS Rater and heating, ventilation, and air conditioning contractor. (2) Increased material costs related to the checklists, especially the U.S. Environmental Protection Agency Indoor airPLUS and WaterSense Efficient Hot Water Distribution requirement. Ceiling - 18" cellulose Walls - 12" open cell spray foam in double stud walls Foundation - R-10 under slab, 3 1/2" closed-cell spray foam at walls Windows - Harvey U=0.20, SHGC=0.22 Infiltration - 1.0 sq in per 100 sq ft Heating - Mini split heat pump, 10.6 HSPF, 23 SEER Cooling - Mini split heat pump, 10.6 HSPF, 23 SEER DHW - 0.97 EF instantaneous propane water heater Ventilation - bathroom exhaust fans as basic option, HRV upgrade option Adams Circle Devens MA 01434 Cavite Street Devens, MA 01434

Array↗

NASA NTRS1991

Millimeter wavelength communications applications for the SEI

The potentially complex missions of the Space Exploration Initiative (SEI) require advanced lunar communications, navigation, and information systems to provide voice, data, and image transmissions. The objectives here are to determine which SEI telecommunications applications will benefit from millimeter wave technology, assess the state of the art in millimeter wave technology, and describe the technology development shortfalls with respect to potential mission time frames. The assumptions for the analysis as well as other non-performance related issues are also presented.

Ponchak, Denise S.↗

NASA NTRS1992

Reaction rate and energy-loss rate for photopair production by relativistic nuclei

The process of e(+/-) pair production by relativistic nuclei on ambient photons is considered. The process is important for cosmic-ray nuclei in interstellar and intergalactic space as well as in galactic and extragalactic compact objects. The rate of this process is given by an integral of the cross section over the photon angular and energy distribution. In the case of isotropic photons, the angular integration is performed to provide an expression for the rate at given photon energy in the nucleus rest frame. The total rate then becomes a single integral of that rate over the photon energy distribution. Formulas are also given for the fractional energy loss of a relativistic nucleus colliding with a photon of a given energy in the rest frame. The nucleus energy-loss rate is integrated over the photon angular distribution in the case of isotropic photons, and simple fits are provided.

Chodorowski, Michal J.↗

NASA NTRS1995

Color evolution from z = 0 to z = 1

Rest frame Stroemgren photometry (3500 A, 4100 A, 4750 A, and 5500 A) is presented for 509 galaxies in 17 rich clusters between z = 0 and z = 1 as a test of color evolution. Our observations confirm a strong, rest frame, Butcher-Oemler effect where the fraction of blue galaxies increases from 20% at z = 0.4 to 80% at z = 0.9. We also find that a majority of these blue cluster galaxies are composed of normal disk or post-starburst systems based on color criteria. When comparing our colors to the morphological results from Hubble Space Telescope HST imaging, we propose that the blue cluster galaxies are a population of late-type, low surface brightness objects which fade and are then destroyed by the cluster tidal field. After isolating the red objects from Butcher-Oemler objects, we have compared the mean color of these old, non-star-forming objects with spectral energy distribution models in the literature as a test for passive galaxy evolution in ellipticals. We find good agreement with single-burst models which predict a mean epoch of galaxy formation at z = 5. Tracing the red envelope for ellipticals places the earliest epoch of galaxy formation at z = 10.

Rakos, Karl D.↗

NASA NTRS2001

Teeing Off With an Entirely New Material

Liquidmetal(R) alloy is part of an entirely new class of vitrified metals, and is also known as metallic glass, or Vitreloy(R). A vitrified metal is a frozen liquid that fails to crystallize during solidification, unlike common metals such as titanium, steel, and aluminum. The technology takes the non-crystalline structure of glass and combines it with the properties of metal, a combination not found in nature, allowing for a product that offers the strength of a metal with the elasticity of a polymer. This unique technology is more than twice as strong as titanium and has a higher elastic limit. Liquidmetal(R) Golf presents this space-age development in a complete line golf clubs. Clubs made with this technology have a lower vibration response along with a softer, more solid feel. Because less energy is absorbed by the club's head upon impact, more energy is transferred directly to the ball. Vitreloy has potential commercial uses in sporting equipment: tennis rackets, bicycle frames, and baseball bats. The material may find applications in the medical industry for the manufacturing of surgical instruments and prosthetics. The Liquidmetal alloy is projected to replace many high performance materials, such as titanium, in the industries of aerospace, defense, military, automotives, medical instrumentation, and sporting goods

Source record↗

NASA NTRS2004

AROTAL Ozone and Temperature Vertical Profile Measurements from the NASA DC-8 during the SOLVE II Campaign

The AROTAL instrument (Airborne Raman Ozone Temperature and Aerosol Lidar) - a collaboration between scientists at NASA Goddard Space Flight Center, and Langley Research Center - was flown on the NASA DC-8 during the SOLVE II Campaign during January and February, 2003. The flights were flown from the Arena Arctica in Kiruna, Sweden. We report measurements of temperature and ozone profiles showing approximately a 600 ppbv loss in ozone near 17.5 km, over the time frame of the aircraft campaign. Comparisons of ozone profiles from AROTAL are made with the SAGE III instrument.

McGee, Thomas J.↗

NASA NTRS2018

Methods and Apparatus for Aggregation of Multiple Pulse Code Modulation Channels into a Signal Time Division Multiplexing Stream

Methods and apparatus are provided for telemetry processing using a telemetry processor. The telemetry processor can include a plurality of communications interfaces, a computer processor, and data storage. The telemetry processor can buffer sensor data by: receiving a frame of sensor data using a first communications interface and clock data using a second communications interface, receiving an end of frame signal using a third communications interface, and storing the received frame of sensor data in the data storage. After buffering the sensor data, the telemetry processor can generate an encapsulated data packet including a single encapsulated data packet header, the buffered sensor data, and identifiers identifying telemetry devices that provided the sensor data. A format of the encapsulated data packet can comply with a Consultative Committee for Space Data Systems (CCSDS) standard. The telemetry processor can send the encapsulated data packet using a fourth and a fifth communications interfaces.

Chang, Chen J.↗